With advantages of energy conservation, environmental friendliness, and long service life, light emitting diodes (LEDs), in most lighting areas, have gradually taken the place of conventional light sources including incandescent light bulbs and halogen lamps which have high energy consumption and short service life. Household appliances such as ovens and microwave ovens require lighting function, but the chamber of the household appliances has a high temperature during working, so it is necessary to substitute LED light sources for conventional light sources.
However, the substitution encounters the following difficulties. LED light sources are cold light sources, and the chips and encapsulating materials thereof are not high temperature resistant, so when the LED light sources are used to substitute for conventional light sources of ovens and microwave ovens, they tend to be damaged in high temperature environment.